Almost 40% of global cancer cases could be prevented, according to a new global study from the World Health Organization (WHO) and its International Agency for Research on Cancer (IARC), published in Nature Medicine on Tuesday.

The study attributed some 7.1 million cancer cases in 2022 to 30 “modifiable risk factors”.

Tobacco was the leading preventable cause of cancer, globally responsible for 15% of all new cases, followed by infections (10%) and alcohol consumption (3%).

Three cancer types – lung, stomach and cervical cancer – accounted for nearly half of all preventable cancer cases in both men and women, globally.

Lung cancer was primarily linked to smoking and air pollution, stomach cancer was largely attributable to Helicobacter pylori infection, and cervical cancer was overwhelmingly caused by human papillomavirus (HPV).

Gender and regional differences

Around 45% of new cancer cases in men could be prevented in comparison to 30% in women, according to the study, which draws on data from 185 countries and 36 cancer types.

In men, smoking accounted for an estimated 23% of all new cancer cases, followed by infections at 9% and alcohol at 4%. Among women globally, infections accounted for 11% of all new cancer cases, followed by smoking at 6% and high body mass index at 3%.

There were also geographical differences. Preventable cancers for women ranged from 24% in North Africa and West Asia to 38% in sub-Saharan Africa. 

Among men, 57% of cancers in East Asia were preventable, while only 26% were in Latin America and the Caribbean at 28%

“This is the first global analysis to show how much cancer risk comes from causes we can prevent,” said Dr Andre Ilbawi, WHO Team Lead for Cancer Control, and author of the study. “By examining patterns across countries and population groups, we can provide governments and individuals with more specific information to help prevent many cancer cases before they start.”

The WHO urged countries to develop “context-specific prevention strategies that include strong tobacco control measures, alcohol regulation, vaccination against cancer-causing infections such as human papillomavirus (HPV) and hepatitis B, improved air quality, safer workplaces, and healthier food and physical activity environments”.

Europe recognises air pollution as cancer agent

Meanwhile, air pollution will be added to the European Code Against Cancer for the first time.

“Air pollution raises our overall cancer risk by 11% and risk of death from cancer by 12%. Poor air quality is the largest environmental threat to human health, killing more people than tobacco, so it’s significant progress that air pollution is now recognised in the latest European Code Against Cancer,” said Nina Renshaw, head of health at the Clean Air Fund.

“This vital change means that institutions and governments across the EU and the World Health Organization’s wider European region now have an even clearer mandate to reduce dangerous air pollution, and in doing so, protect people’s health.

“With 99% of people worldwide currently breathing harmful air – contributing to respiratory diseases, strokes, heart attacks, and dementia, as well as stillbirths and miscarriages – it’s essential to address the interconnections between air quality and urgent health challenges.

“Clean air measures positively impact public health almost immediately, resulting in reduced hospitalisations – and ultimately in fewer people developing chronic health conditions such as lung cancer.”

Image Credits: Gavi.